#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2018 crane <crane@crane-pc>
#
# Distributed under terms of the MIT license.

"""

"""


class Solution:
    """
    @param a: An integer
    @param b: An integer
    @return: The sum of a and b
    """
    def aplusb(self, a, b):
        if a == 0: return b
        if b == 0: return a

        stay = a ^ b
        carry = (a & b) << 1
        return self.aplusb(stay, carry)


def main():
    print("start main")

if __name__ == "__main__":
    main()
